In this proposal, four NIH-funded faculty members in the Department of Biology of the Massachusetts Institute of Technology request funding to replace much of the aging equipment of the department's Structural Biology Core Facility. The requested funding will be used to upgrade this dilapidated facility into a state-of-the-art, multi-user core facility capable of serving the needs of the principal investigators and other members of the MIT structural biology community for many years. The proposed upgrade would replace the old generator, optics and cryo-system with modern instruments. The R-AXIS IV detector currently in use would be maintained and used with the new, equipment. The specific instruments requested in this proposal are a Rigaku MicroMax 007 generator, an Oxford Cryosystems CSCryostream700EX sample cooler, and Rigaku/Osmic VariMax Cu optics. The old generator needs replacing because it rapidly approaching the end of its useful lifetime. More importantly, the new generator can provide about twice the useable flux for the typical frozen crystal. Combined with the new brighter source, the new, vastly superior, optics will dramatically improve the facility's capability to collect high quality data from small or weakly diffracting crystals and significantly increase the overall capacity of the system to generate crystallographic data. The new cryo-system is desperately needed because the performance of old system has become, at best, marginal. The new equipment will replace existing instrumentation in the Facility on the fifth floor of the Koch Biology Building, where it is readily accessible to all of the primary users and the MIT biology community as a whole. The new instrumentation will dramatically improve the productivity of principal investigators' structural biology research, provide capability not currently available anywhere at on campus, and contribute to providing the best possible training of the next generation of structural biologist from MIT.